Tonight while in the middle ring (39) I used all ten cogs in the rear. Even though we were going up a really steep 3 mile grade, I decided to stay in the middle ring unless I absolutely needed the granny. Tonight I did not. I hear some slight noise when using the biggest cog and the smallest cog. Was I cross chaining? If so, what's the point of all those gears in the back if I can't use them? My LBS guy says it's no problem to use them all in that middle ring.